Load-bearing member of reinforced thermoplastic

Abstract

Apparatus is disclosed for molding a load-bearing element of reinforced thermoplastic material provided from a material charge including a thermoplastic matrix material of a non-permeable plastic membrane and a reinforcement material, the apparatus including a molding tool having first and second molding surfaces which are juxtaposed in a closed molding position producing at least one internal cavity having dimensions corresponding to the load-bearing element, a heater for heating the matrix material to a temperature above its softening temperature, a pressurizer for providing a pressure or vacuum force to urge the matrix material against at least one of the molding surfaces with the reinforcement material therebetween in order to urge the reinforcement material against one of the first and second molding surfaces to mold and consolidate the material charge. Methods for molding these load-bearing elements and novel load-bearing elements themselves are also disclosed.

What is claimed is:  
     
       1. A method for molding a load-bearing element comprising providing a molding tool including a first molding surface and a second molding surface forming a closed molding position when said first and second molding surfaces are juxtaposed against each other, introducing a material charge between said first and second molding surfaces comprising at least one layer of thermoplastic matrix material comprising a non-permeable plastic membrane having a predetermined softening temperature and a reinforcement material, with said reinforcement material disposed between said thermoplastic matrix material and at least one of said first and second molding surfaces, molding said material charge between said first and second molding surfaces with areas of said thermoplastic matrix material clamped within said molding tool to provide a seal, heating said material charge to an elevated temperature exceeding said predetermined softening temperature, providing pressure or vacuum force for urging said matrix material against said at least one of said first and second molding surfaces with said reinforcement material therebetween to mold and consolidate said material charge, and cooling said load-bearing element to a temperature below said predetermined softening temperature wherein at least one additional load-bearing element is incorporated in said material charge. 
     
     
       2. A load-bearing element comprising reinforced plastic including a thermoplastic matrix and reinforcement material simultaneously consolidated during a molding process wherein a plurality of layers of said reinforced plastic surround at least one cavity formed during said molding process by the application of a pressure or vacuum force on said thermoplastic matrix material in a heated state, said thermoplastic matrix material comprising a non-permeable plastic membrane which presses said reinforcement material against the surfaces of a molding tool during said molding process, wherein said load-bearing element includes a plurality of cavities formed during the molding process, each cavity forming a strengthening member of said load-bearing element. 
     
     
       3. An apparatus for molding a load-bearing element comprising reinforced thermoplastic material provided from a material charge comprising at least one layer of thermoplastic matrix material comprising a non-permeable plastic membrane having a predetermined softening temperature and a reinforcement material, said apparatus comprising a molding tool including a first molding surface and a second molding surface whereby when said first and second molding surfaces are juxtaposed in a closed molding position at least one internal cavity having dimensions corresponding to said load-bearing element is formed therebetween, means for urging said first and second molding surfaces into said closed molding position, heating means for heating said matrix material to a temperature above said predetermined softening temperature, and matrix material molding means for providing a pressure or vacuum force for urging said matrix material against at least one of said first and second molding surfaces with said reinforcement material therebetween to thereby urge said reinforcement material against said at least one of said first and second molding surfaces to mold and consolidate said material charge, wherein said at least one of said first and second molding surfaces includes compressing means for compressing predetermined regions of said material charge so as to provide a plurality of internal cavities between said predetermined regions and to provide compressed regions of said material charge including said non-permeable plastic membrane. 
     
     
       4. A method for molding a load-bearing element comprising providing a molding tool including a first molding surface and a second molding surface forming a closed molding position when said first and second molding surfaces are juxtaposed against each other, introducing a material charge between said first and second molding surfaces comprising at least one layer of thermoplastic matrix material comprising a non-permeable plastic membrane having a predetermined softening temperature and a reinforcement material, with said reinforcement material disposed between said thermoplastic matrix material and at least one of said first and second molding surfaces, molding said material charge between said first and second molding surfaces with areas of said thermoplastic matrix material clamped within said molding tool to provide a seal, heating said material charge to an elevated temperature exceeding said predetermined softening temperature, providing pressure or vacuum force for urging said matrix material against said at least one of said first and second molding surfaces with said reinforcement material therebetween to mold and consolidate said material charge, cooling said load-bearing element to a temperature below said predetermined softening temperature, and compressing predetermined regions of said material charge so as to provide a plurality of internal cavities between said predetermined regions and compressed regions of said material charge at said predetermined regions including said non-permeable membrane. 
     
     
       5. A load-bearing element comprising reinforced plastic including a thermoplastic matrix and reinforcement material simultaneously consolidated during a molding process wherein a plurality of layers of said reinforced plastic surround at least one cavity formed during said molding process by the application of a pressure or vacuum force on said thermoplastic matrix material in a heated state, said thermoplastic matrix material comprising a non-permeable plastic membrane which presses said reinforcement material against the surfaces of a molding tool during said molding process, wherein said plurality of layers of said reinforced plastic surround a plurality of cavities separated by compressed regions of said reinforced plastic.